You can choose which projects in Jira have their attachments encrypted. Projects can be encrypted by following the steps below.
Select Add-ons from the Jira Administration menu.
Select Configuration under Encryption for Jira in the left sidebar.
Select Encrypting attachments from the progress bar.
On this screen, you can choose to encrypt all attachments in your Jira instance, or you can only encrypt the attachments in selected projects.
To encrypt all attachments select the toggle.
To encrypt attachments in selected projects, select the projects field and select the check boxes for all the projects you wish to encrypt. You can use the search to find the projects you want.
Select Save and continue.
Completing this step encrypts the data within the database. However, it will remain visible inside Jira unless you have changed the Visibility Permissions.